cloexec.c

/* closexec.c - set or clear the close-on-exec descriptor flag Copyright (C) 1991, 2004-2006, 2009-2010 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. The code is taken from glibc/manual/llio.texi */#include <config.h>#include "cloexec.h"#include <errno.h>#include <fcntl.h>#include <unistd.h>/* Set the `FD_CLOEXEC' flag of DESC if VALUE is true, or clear the flag if VALUE is false. Return 0 on success, or -1 on error with `errno' set. Note that on MingW, this function does NOT protect DESC from being inherited into spawned children. Instead, either use dup_cloexec followed by closing the original DESC, or use interfaces such as open or pipe2 that accept flags like O_CLOEXEC to create DESC non-inheritable in the first place. */int
set_cloexec_flag (int desc, bool value)
{
#ifdef F_SETFDint flags = fcntl (desc, F_GETFD, 0);
if (0 <= flags)
{
int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC);
if (flags == newflags
|| fcntl (desc, F_SETFD, newflags) != -1)
return 0;
}
return -1;
#else /* !F_SETFD *//* Use dup2 to reject invalid file descriptors; the cloexec flag will be unaffected. */if (desc < 0)
{
errno = EBADF;
return -1;
}
if (dup2 (desc, desc) < 0)
/* errno is EBADF here. */return -1;
/* There is nothing we can do on this kind of platform. Punt. */return 0;
#endif /* !F_SETFD */
}
/* Duplicates a file handle FD, while marking the copy to be closed prior to exec or spawn. Returns -1 and sets errno if FD could not be duplicated. */int
dup_cloexec (int fd)
{
return fcntl (fd, F_DUPFD_CLOEXEC, 0);
}